MEM: almost 100% (16GB) ----------------- maybe this is the bottleneck. writing concerns Memtable and SSTable in memory.
在 2010年6月2日 上午9:48，Shuai Yuan <yuansh...@supertool.net.cn>写道： > 在 2010-06-01二的 15:00 -0500，Jonathan Shook写道： > > Also, what are you meaning specifically by 'slow'? Which measurements > > are you looking at. What are your baseline constraints for your test > > system? > > > Actually, the problem is the utilizaton of resources(for a single > machine): > CPU: 700% / 1600% (16 cores) > MEM: almost 100% (16GB) > Swap: almost 0% > Disk IO(write): 20~30MB / 200MB (7.2k raid5, benchmarked previously) > NET: up to 100Mbps / 950Mbps (1Gbps, tuned and benchmarked previously) > > So the speed of generating load, about 15M/s as reported before seems > quite slow to me. I assume the system should get at least about 50MB/s > of Disk IO speed. > > MEM? I don't think it plays a major role in this writing game. What's > the bottleneck of the system? > > P.S > about Consistency Level, I've tried ONE/DCQUORUM and found ONE is about > 10-15% faster. However that's neither a promising result. > > Thanks! > > Kevin > > > > 2010/6/1 史英杰 <shiyingjie1...@gmail.com>: > > > Hi, It would be better if we know which Consistency Level did you > choose, > > > and what is the schema of test data? > > > > > > 在 2010年6月1日 下午4:48，Shuai Yuan <yuansh...@supertool.net.cn>写道： > > >> > > >> Hi all, > > >> > > >> I'm testing writing speed of cassandra with 4 servers. I'm confused by > > >> the behavior of cassandra. > > >> > > >> ---env--- > > >> load-data app written in c++, using libcassandra (w/ modified batch > > >> insert) > > >> 20 writing threads in 2 processes running on 2 servers > > >> > > >> ---optimization--- > > >> 1.turn log level to INFO > > >> 2.JVM has 8G heap > > >> 3.32 concurrent read & 128 write in storage-conf.xml, other cache > > >> enlarged as well. > > >> > > >> ---result--- > > >> 1-monitoring by `date;nodetool -h host ring` > > >> I add all load together and measure the writing speed by > > >> (load_difference / time_difference), and I get about 15MB/s for the > > >> whole cluster. > > >> > > >> 2-monitoring by `iostat -m 10` > > >> I can watch the disk_io from the system level and have about 10MB/s - > > >> 65MB/s for a single machine. Very big variance over time. > > >> > > >> 3-monitoring by `iptraf -g` > > >> In this way I watch the communication between servers and get about > > >> 10MB/s for a single machine. > > >> > > >> ---opinion--- > > >> So, have you checked the writing speed of cassandra? I feel it's quite > > >> slow currently. > > >> > > >> Could anyone confirm this is the normal writing speed of cassandra, or > > >> please provide someway of improving it? > > >> -- > > >> Kevin Yuan > > >> www.yuan-shuai.info > > >> > > >> > > > > > > > > > > -- > Kevin Yuan > www.yuan-shuai.info > > >
